Engines, including diesel engines, gasoline engines, natural gas engines, and other engines known in the art, may exhaust a complex mixture of air pollutants. The air pollutants may be composed of both solid materials, such as, for example, particulate matter, and gaseous material, which may include, for example, oxides of nitrogen, such as NO and NO2 (commonly referred to collectively as “NOx”).
Due to increased environmental concerns, exhaust emission standards have become more stringent. The amount of particulate matter and gaseous pollutants emitted from an engine may be regulated depending on the type, size, and/or class of engine. In order to meet these emissions standards, engine manufacturers have pursued improvements in several different engine technologies, such as fuel injection control, engine management, and air induction, to name a few.
In addition, engine manufacturers have developed devices for treatment of engine exhaust after it leaves the engine (sometimes referred to as “after-treatment”). For example, engine manufacturers have employed exhaust treatment devices that utilize catalysts to convert one or more components of the exhaust to different, more environmentally-friendly compounds. Catalyst-based exhaust treatment devices have been developed for reducing or removing NOx from the exhaust stream. In some systems, NOx may be reduced by selective catalytic reduction (commonly referred to as “SCR”). In such systems, a gaseous or liquid reductant (most commonly urea, a urea/water solution, or a hydrocarbon, for example, diesel fuel, and/or ammonia gas (NH3)) may be added to a catalyst-based device, where it is chemically broken down into ammonia (NH3) that is then stored in (or on) the catalyst. The ammonia stored in the catalyst reacts with NOx in the exhaust stream to convert the NOx to Nitrogen (N2) and water (H2O).
Although SCR can be an effective method for reducing NOX, it can also be difficult to ensure that the reductant has been uniformly distributed to the catalyst to adequately reduce the amount of NOX present within the exhaust gas stream.
One attempt to uniformly distribute the injection of reductant is described in PCT Application Publication No. WO 98/28070 (the '070 publication) to Peter-Hoblyn et al. published on Jul. 2, 1998. The '070 publication discloses an exhaust system for reducing NOX emissions from a lean-burn engine, such as a diesel engine. The exhaust system includes an exhaust pipe of an engine and an SCR catalyst located within the exhaust pipe. The exhaust system also includes a plurality of injectors positioned on the exhaust pipe. Supply lines feed each injector an aqueous urea solution after being heated by a separate heating element, and the injectors are configured to inject the aqueous urea solution into the exhaust pipe upstream of the SCR catalyst.
Although the method of the '070 publication may provide improved mixing of a reductant injected into an exhaust stream, it may have limitations. For example, having multiple supply lines to feed a reductant to the injectors may create an uneven distribution of the reductant to each injector, which may in turn produce a non-uniform distribution of reductant injected into the exhaust stream. In addition, multiple feed lines may increase the chance of complications associated with reductant delivery to the injectors.
The fluid delivery system of the present disclosure is directed towards improvements to the existing technology.